Micro machined, integrated radio frequency (RF) switches are favored for telecommunications applications because they provide a large dynamic range between on-state and off-state impedances in the RF regime while avoiding bulk and high cost. However, because of the proximity of the electrodes in such micro machine switches, there is a problem with arcing induced stiction. This problem becomes significantly increased in MEMS in which the RE switches are mechanically operated at high speed and must handle high power signals at frequencies of above 5 GHzs.
MEMS systems described in U.S. Pat. No. 5,578,976 are only able to handle low power RF signals at signal frequencies only up to 4 GHzs while maintaining a relatively minimum insertion loss in the "on" state and relatively high electrical isolation in the "off" state. The patented micro machined switches contain a micro machined armed cantelever actuator which is fixed at one end as shown in FIG. 1 reproduced from he '976 patent. In operation, as the cantelever actuator is switched on, only a line contact is made between the shorting bar and fixed electrical contacts of the switch. Therefore, the load carrying capacity of the micro switch is quite limited due to arcing and welding problems (See FIG. 2).
Micro switches that are based on a membrane structure and are fixed on a plurality of sides to the substrate are described in U.S. Pat. No. 5,619,061. The membrane structure is susceptible to thin-film stresses and has little tolerance for deflections which may be produced during the in-situ processing of the membrane. Therefore, functional failures of the devise are commonplace.
Thus, there still exists a need in telecommunication systems for micro electromechanical switches that provide a wide dynamic impedance range from on to off at signal frequencies from DC up to at least 50 GHz and that have a large load carrying capacity.